The invention relates to a method for the fine tuning of a passive electronic component which comprises at least a carrier substrate and at least one electrically conducting layer, in which method a heating effect is achieved locally on the electrically conducting layer by means of focused laser emission, and the electrically conducting layer is locally brought into an electrically non-conducting state.
The development of numerous electronic devices is characterized by the following trends: miniaturization, higher reliability, lower or at least constant prices accompanied by an increasing functional level. In spite of all efforts at digitization, the number of passive components in many appliances in the field of consumer electronics, for example in TV sets or video recorders, is found to account for 70% of all components present. The increasing miniaturization in particular has the effect that fluctuations in the basic materials and in the manufacturing process of the passive electronic components have a comparatively great influence on the final electrical specifications.
The thin layer technology, where mainly vaporizing and sputtering methods are used for providing the electrically conducting layers, renders it possible to manufacture, for example, resistors with a tolerance range of xc2x15%. A better process control in the manufacture of the passive electronic components causes higher process costs.
A possibility of keeping the manufacturing costs as low as possible is formed by the manufacture of passive electronic components such as capacitors, resistors, and inductances with a wide specification range which are then set for the desired final specifications by means of corrective aftertreatments (fine tuning).
DE 38 43 980 discloses a method for the fine tuning of a capacitor which comprises a laser-transparent carrier substrate, a lower electrode, an insulation layer, and an upper electrode by means of laser emission applied to the lower electrode. The laser emission causes a heating effect on the lower electrode, which is made of aluminum or tantalum, such that electrode material is oxidized and is brought into an electrically non-conducting state.
The disadvantage of the method described above is that the metals used, aluminum and tantalum, limit the application of the method described to capacitors, because these metals are not suitable for the realization of resistors on account of their low resistivity values.
The invention has for its object to develop a general method by means of which the fine tuning of the electronic final specifications of a wide variety of passive electronic components can be carried out.
This object is achieved by means of a method for the fine tuning of a passive electronic component which comprises at least a carrier substrate and at least one electrically conducting layer, in which method a heating effect is achieved locally on the electrically conducting layer by means of focused laser emission, and the electrically conducting layer is locally brought into an electrically non-conducting state, in that the electrically conducting layer comprises a material with a conducting nitride, or a conducting oxynitride, or a semiconductor, or chromium, which layer is converted into a locally electrically non-conducting material by the heating effect.
This method involving the use of the materials mentioned above as the electrically conducting layers has the advantage that the fine tuning of the final electrical specifications takes place without a removal of material and can thus still be achieved also after the incorporation of the component in an electrical circuit.
It may be preferred that the passive electronic component which is fine-tuned is a resistor.
It is possible by means of the method described above to set accurately a desired rated resistance value. A very narrow tolerance range of 1% or better can be achieved thereby.
It may be preferred that the passive electronic component which is fine-tuned is a capacitor which comprises at least two electrically conducting layers and at least one dielectric.
Since the capacitance value of a capacitor depends inter alia on the effective surface areas of the conducting layers, i.e. the electrodes, it is possible to tune also the capacitance value of the capacitor by means of a reduction of the surface areas of the conducting layers.
It may be preferred that the passive electronic component which is fine-tuned is an inductance.
The inductance value can be adjusted by changing the line widths, and thus the line interspacings.
It may furthermore be preferred that the passive electronic component comprises at least a first and a second current supply contact.
Each passive electronic component can be coupled to further components of a circuit or to a measuring device for determining the electronic final specification at its current supply contacts.
The invention further relates to a method of structuring an electrically conducting layer by means of focused laser emission, in which method a heating effect is achieved locally on an electrically conducting layer by means of a laser beam, and the electrically conducting layer is locally brought into a non-conducting state, characterized in that the electrically conducting layer comprises a material with a conducting nitride or a conducting oxynitride, or a semiconductor, or chromium, which material is converted into a locally electrically non-conducting material by the heating effect.
This method has the advantages that it is less expensive than a structuring by means of photolithographical processes combined with dry or wet etching steps, and that no material removal takes place, but instead the electrically conducting material is converted into an insulating material.
The application of the electrically conducting layer structured in accordance with the method described above in a conductive circuit, a resistor, a capacitor, or an inductance is advantageous because the structuring takes place without material removal and can accordingly still take place after incorporation in an electrical circuit.